Scrolling issue in SAP Desktop application


I am currently working on the SAP desktop application which consist of 2 page scroll down.

The situation is that

.1. I need to select the line number from the software, scroll down and then edit the quantity. For editing the quantity I need to scroll down the outside section of the page and then I able to edit the quantity.(there are 2 sections and both contain scrolls 1. Contains description of the products 2. Contains the main part where you see the "quantity section " and you write the quantity in that section )
2. After editing the quantity I need to scroll up again to select the 2nd description and edit the quantity for 2 product

So how do I cope with multiple scrollings in SAP software ?? how do I do that

If my question is unclear please revert back thanks

If anyone has understood and know the solution please provide for this part

Did you tried page down option by sendhot key ?

Yes I tried it worked for one scroll bar which contains description. But I am not able to do the other one for which I want to edit the quantity.